Kemess North Supplementary Alternatives Workshop.

Kemess NorthKemess North

SupplementarySupplementaryAlternatives Workshop

Workshop Purpose

Communicate the alternatives available and assess alternatives together.

To get federal and provincial agency agreement that Kemess North waste rock and tailings is PAG and best management practices for ARD prevention is sub-aqueous disposal.

To confirm the final alternative(s) and agree on the review process for the environmental assessment.

Alternatives Assessment to Date

• October 2003 - Project Description Submitted• November 2003 – First Agency Meeting• December 2003 – Pre-feasibility Alternatives

Assessment Submitted• January 2004 – Stakeholders Alternatives

Meeting• February – March 2004 – Feedback and

Reassessment• March 2004 – Supplementary Alternatives Report• April 2004 – Agency Alternatives Workshop

Alternatives PresentationAgenda

• General requirements• Description of all alternatives• Summary of main alternatives and

combinations of alternatives• Comparison of alternatives (cost and

risk)• Environmental comparison of

alternatives

CEAA Alternative Assessment Requirements

• What is the project need and purpose?• What are the alternative means of

carrying out the project?• What are the alternatives to the

project?

Project Need and PurposePurpose - To produce copper/gold

concentrate in an environmentally responsible manner that returns an economic benefit to the company.Metal Mines in

BCCommodity Production Commenced

ProductionProjected Closure

Kemess SouthOpen pit

CopperGold

50,000 t/d 1998 2008

Highland ValleyOpen pit

Copper, MolybdenumSilver, Gold

136,000 t/d 49.9 Mt milled in 2002 181,300 t copper produced in 2002

1986 2010

Myra FallsUnderground

Copper, Zinc, LeadGold, Silver

4000 t/d 1966 2012+

Eskay CreekUnderground

GoldSilver

300 t/d 352,070 oz. gold, 17.0 M oz. silver in 2003

1995 2006

HuckleberryOpen pit

Copper, ZincMolybdenum

21,000 t/d 1997 2007

EndakoOpen pit

Molybdenum 27,000 t/d 1965 2012+

Alternative Means of Carrying Out the Project

Mining Methods – Underground mining is too expensive for the ore grades.

Plant Optimization – Milling will be increased to meet the economic requirements of the deposit.

Waste Management Options – Typical of mining, waste management alternatives are a critical project component.

Engineering Guidelines for Alternatives

• ~320 Mt (previously 250 Mt) of potentially acid generating tailings

• ~200 Mt (previously 375 Mt) of potentially acid generating waste rock• 75% to 90% of waste rock will be acid generating

if not kept submerged under water.

• Minimize number of sites.• Minimize heights and complexities of dams.• Minimize water management, particularly

on closure.

Environmental Guidelines for Alternatives

• Minimize footprint.• Minimize aquatic and terrestrial impacts.• Minimize metal leaching and ARD.• Minimize long term closure risk.• Sustainability. (Sustainable Development

defined as development that meets the needs of the present, without compromising the ability of future generations to meet their own needs.) – continuation of economic benefits

ARD Prevention – Industry Accepted Methods

• Provincial ARD Guidelines – “the storage location must remain permanently flooded and geotechnically stable.”

• Natural Resources Canada and MEND – “The target is for new mines to open without long-term concerns about acidic drainage upon closure.”

Underwater Facilities

Elliot Lake area tailings


Equity Silver Tailings Pond


Eskay Creek Waste Rock Disposal – Albino Lake and

Tom MacKay Lake


Musselwhite, Ontario

Flooded and Reclaimed Site

Dennison Mine – Elliot Lake, ON

Other Mines Affecting Lakes

Diavik

Other Mines Affecting Lakes

Ekati

Underwater Facilities and Research

Louvicourt Tailings Pond

ARD Control – Covers & Treatment

Equity Silver: Low permeability glacial till cover. Marginal improvement in ARD control.

• Cover concerns with:• Freeze-thaw• Plants (roots) animals• Alternative groundwater

paths• Erosion• Cover can minimize seepage

but rarely provides an oxygen barrier to limit ARD.

• Water Treatment Plant: likely hundreds of years of liability.

Waste Quantities Comparison (source: Minfile)

• Bell Copper – 70 Mt PAG tailings• Huckleberry – 36 Mt PAG tailings• Equity Silver – 33 Mt PAG tailings• Kemess South – 89 current, ~200 Mt

expected PAG tailings• Kemess North – need to dispose of

>300 Mt PAG tailings and >200 Mt PAG waste rock

Alternative Identification

• Considered all sites within about a 10 km radius that could store some or all of the waste.

• Integrate/consider technology variations.

• Considered combinations of alternatives.

Screened TechnologiesTailings

• Thickening & paste: reduced volume, however still requires a dam and saturation of sulphides.

• Dewatered: reduced volume & “dry” stack, however still need to compact “dam” support zone. ARD from partially saturated tailings.

• Co-disposal with waste rock: Only a portion of the tailings could be mixed. Concerns with mixing, and ARD from the final mixed product.

• Desulphidize Tailings: Used to produce construction sand from cycloned tailings. Can be used for capping.

Screened TechnologiesARD Control

• Saturate under water: Preferred ARD control method. Base consideration for this project.

• Cover: Poor success rate (e.g. Equity Silver Mine); concern with long term integrity of cover and potential for “alternative” seepage paths.

• Water Treatment: Concerns with long term operation, maintenance of facility (hundreds of years) and sludge disposal. Need disposal site for sludge.

• Limestone mixing: Limited ability of lime to properly mix and balance ARD.

Screening Process

1. Layouts and cost estimates for all alternatives.

2. Risk Assessment using Failure Modes Effects Analysis (FMEA) procedures which are recommended by the Mining Association of Canada and adopted by numerous Regulatory Authorities in Canada and USA.

3. Environmental Comparison, including compensation potential.

Location Plan of Selected Screening Sites

• Tailing Alternatives (330 Mt)• Raise existing tailings dam• Infill existing open pit (25% of

tailings)• Raise open pit• Sites L & M (close to Kemess

South Mine)• Site C and Kemess Lake• Duncan Lake (25% of tailings)

• Waste Rock Alternatives (250 Mt)• North & Northeast Dumps• Site C• Duncan Lake (50% of waste

rock)

Screened LocationsExisting Tailings Facility

Advantages & Disadvantages

• Stores tailings only.• Limited new disturbance.• Dam safety risk due to very

low foundation shear strength. Slopes 5.5H:1V +

• Toe of dam encroaches on Mill Creek.

• High pumping head.

Project Components• Dam raise from 145 m to

170+ m high.

• Pumping head 310 m• New water diversion dams

and diversion canals/pipelines.• Continue to use de-

sulphidized cycloned sand for

construction of dam.• Cost $400 million +

Screened LocationsOpen Pit - Tailings


• Stores tailings only (max. 250 Mt)

• Limited new disturbance.• Dam safety risk with 100 m

high dam above the plantsite.• Toe of dam “encroaches” on

Kemess Creek.

Project Components• Construct 100 m high dam

around the open pit.• Use de-sulphidized

cycloned sand for dam construction.

• Pumping head 120 m.• Some potential for weak

clay layers in the dam foundation.

• Cost: $200 million

Screened LocationsSite L - Tailings


• Stores tailings only ( 250 Mt +)

• Limited new disturbance.• Very poor storage/dam ratio

due to presence of mine waste rock and topograhy.


in the vicinity of the existing waste dump.

• Use de-sulphidized cycloned sand for dam construction.

• Pumping head 120 m.• Potential for weak clay

layers in dam foundation.• Cost: $785 million +

Screened LocationsSite M - Tailings


• Stores tailings only (max. 250 Mt +)

• Disturbance of terrestrial/forested areas and wetland.

• Poor storage/dam ratio due to topograhy.


in the vicinity of the existing airport and power line.


• Pumping head 120 m.• Potential for weak clay

layers in dam foundation.• Cost: $440 million +

Screened LocationsSite F - Kemess Lake - Tailings


• Infills Kemess Lake.• Stores tailings only (max. 250

Mt)• Disturbance of

terrestrial/forested areas and wetland.

• Very difficult geotechnical conditions.


across south end of Kemess Lake.


• Pumping head 170 m.• Weak foundation.• Unstable bedrock geology

in left bank of impoundment.

• Cost: $335 million

Screened LocationsSite C - Tailings/Waste Rock


• Could be raised 70 m to store mine waste rock.

• Disturbance of terrestrial/forested areas and wetland. Significant wildlife corridor.

• Long haul distance for mine waste rock and high pumping heads for tailings.

Project Components• Construct two 100 m high

dam• Use de-sulphidized

cycloned sand for dam construction.

• Pumping head 260 m.• Cost: $260 million +

tailings; $775 million waste

rock/tailings

Screened LocationsDuncan Lake - Tailings and Waste

RockAdvantages &

Disadvantages• Loss of Duncan Lake habitat.• Sustainable – allows for future

use of regional resources.• Most efficient site.

Project Components• Construct one 80 m high

dam and two 20 m high dams to store all tailings and waste rock.

• Pumping head 160 m.• Cost: $60 million tailings,

$140 million waste rock/tailings

Screened LocationsAttycelley - Tailings and Waste

RockAdvantages &

Disadvantages• Loss of Attycelley stream

habitat.• Impact on terrestrial and

wildlife corridor.• Difficult geotechnical

conditions and difficult seepage control.

• Large watershed increase closure water control risk.

Project Components• Construct 100 m high

starter dam, raise to 160 m high.

• Pumping head 200 m.• Foundation conditions

expected to be complex.• Dam use de-sulpidized

cycloned sand.• Cost: $625 million waste

rock/tailings

Screened LocationsNE Cirque – Waste Rock


• Geotechnical risk of water dam.

• Long term risk of ARD from cover and treatment alternatives.

• Lowest haulage cost.• Limited disturbance of

terrestrial environment.

Project Components• 200 m high waste rock

pile• ARD controlled by:

• Water dam at downstream toe.

• Low permeability covers.• Water treatment and

sludge disposal.

• Costs $125 million+

SITE DESCRIPTION OR TECHNOLOGY

CONSIDERED USE REASON FOR CONCERN

Thutade Lake Waste rock disposal No containment for controlling contaminant release or treating contaminants.

Thutade Lake Tailings disposal No containment of contaminants.

Valleys on far side of Thutade Lake

Tailings disposal Tailings pipeline across Thutade Lake is expensive and pipeline breaks cannot be contained.

Mainstem Kemess Creek just upstream of the plant site

Waste rock and /or tailings disposal Complex and potentially weak foundations for a high dam. Complex water management for a large catchment area (>100 km2)

Site H, northeast of existing mine in the Kemess Creek watershed

Potential option for containment of 250 Mt of tailings or waste rock

Very high dam in relation to containment volume. Dam heights greater than 200 m

Cirque immediately west of the open pit

Temporarily store waste rock during operations and backfill in the North pit after closure

18% of the waste rock is already producing acid and the onset of ARD in 54% of waste rock is expected within the mine life; therefore, any temporary storage would have to be lined and have a drainage collection and treatment system

Mini-pit Reduced waste volumes Not economic since all ore reserves are at bottom of proposed pit. There is no reserve cut-off that could justify a smaller pit.

North Dump Dry cover land disposal of waste rock

Dry covers have not had enough success in BC to ensure prevention of ARD given the extreme weather conditions.

NE Cirque Flooded waste rock storage Unacceptable long-term risk for a 200m waste rock and water-retaining dam.

Tailings Sulphides Removal (desulphurization)

Reduced ARD potential of tailings Sulphides can be removed from cycloned sand,.

Thickened tailings Reduced storage space requirements Thickened tailings could be considered in the future for optimizing the final design. The storage reduction could be approximately 10% but does not affect the overall alternatives assessment.

Paste tailings Reduced storage space requirements No significant benefit in storage or dams. Process and transport costs are prohibitively high for paste tailings for this grade of ore.

Limestone Blending Neutralization of ARD for land disposal of waste rock

ARD prevention is not effective, because blending is technically difficult and the limestone quickly loses its effectiveness.

Alternatives for Both Tailings and Waste Rock

Supplementary Alternatives

1. Upper Attycelley2. Open Pit/TSF/Site M3. Duncan Lake

Alternative Assessment1. Site C2. On-land dump

w/treatment, open pit/TSF

Alternatives Summary of Risk Points

Comparison of AlternativesRisk and Cost

ALTERNATIVERisk Points Cost

$ Million

Attycelley Creek 735 625

Open pit/Site M/TSF 678 995

Duncan Lake 417 135

Site C 1,317 775

Open pit/TSF/NE Dump with treatment

1,401 325+

Environmental ComparisonCriteria

• Aquatic effects• Terrestrial effects• Footprint of

disturbance• ARD prevention• Contaminant

control• Dam stability

• Closure• Sustainability• Cost• Risk• Ability to

compensate and mitigate

Environmental Comparison

Kemess North Area

Kemess North Post Closure

Alternatives to the Project

1. No Kemess North Project2. Develop Kemess North Project

Developing Kemess North maximizes the use of the resources and infrastructure that already exist.

Northgate has a responsibility to exploit the resource in an environmentally safe and profitable manner.

Path Forward

Underwater Disposal of Potentially Acid Generating Waste

Alternative(s)

Update Environmental Comparison of Main Alternatives

Review Process

Geologic Cross-Section

Kemess North Supplementary Alternatives Workshop.

Documents

Transcript of Kemess North Supplementary Alternatives Workshop.